Several thousand people gathered in Paris, Marseille, Bordeaux and Montpellier.
However, the disruption has remained fairly small-scale. Most of the arrests were made in or around Paris, where about 1,000 protesters – many masked or wearing balaclavas – clashed with police outside Gare du Nord train station.
Some tried to enter the station but were thwarted by agents who fired tear gas, French media report.
Many protesters chanted political slogans against President Emmanuel Macron and Lecornu. Several carried placards against the war in Gaza.
The nebulous movement Let’s Block Everything appears to have been born on social media some months ago and gained momentum over the summer, when it encouraged people to protest against Bayrou’s €44bn (£38bn) budget cuts.
The movement has a distinct left-wing character. Its demands include more investment in public services, taxation for high income brackets, rent freezes and Macron’s resignation.
In the lead-up to Wednesday’s protests, Let’s Block Everything urged people to take part in acts of civil disobedience against “austerity, contempt and humiliation”.
A group of young protesters outside Gare du Nord told the BBC they were taking to the streets in “solidarity” with people in precarious situations across France.
“We are here because we are very tired of how Macron has been handling the situation” of France’s spiralling debt, said Alex, 25, adding he had no faith in the new prime minister not to “repeat the cycle”.